A semiconductor device is manufactured using a wafer through several hundreds of manufacturing operations. Therefore, after performing various operations for manufacturing the semiconductor device on the wafer, resultant products of the manufacturing process steps are inspected or measured within a short time.
As the semiconductor manufacturing process is becoming highly integrated, development of 3D profile measuring techniques of semiconductor micro patterns or complex structures is under way. In recently developed memory and logic products, wafers are fabricated using micro processing technology with a linewidth of 20 nm or less, and a technique for monitoring high-speed micro-patterning is required to improve the yield and quality of wafers. Process failure inspection and profile measurement techniques are largely divided into an optical method and an electron beam method. Of the two methods, the optical method has a more advantageous inspection speed. However, according to the recent trend toward patterning with a linewidth of less than the optical resolution level, the traditional optical method imposes a limitation in 3D profile measurement. To address this issue, an optical critical dimension (OCD) technique is proposed to extract a profile through electromagnetic analysis of the light scattered from micro patterns and may be applied to 3D profile analysis.